1. Field of the Invention
The present invention relates to an apparatus for and a method of measuring motion characteristics of a head gimbal assembly incorporated in a hard disk drive (HDD) of an information processing unit such as a computer.
2. Description of Related Art
A hard disk drive includes a hard disk and a head gimbal assembly including a head suspension, a flexure, a slider and the like. When the hard disk is rotated at high speed, the slider of the head gimbal assembly slightly floats from the surface of the hard disk and a transducer incorporated in the slider writes and reads data to and from the hard disk.
The hard disk drive usually employs a load/unload mechanism to load the slider onto tracks of the hard disk when the hard disk is rotated and unload the slider out of the tracks when the hard disk is stopped.
The load/unload mechanism employs a ramp block made of resin and arranged in the vicinity of the periphery of the hard disk. When the hard disk is stopped, the head gimbal assembly is retracted onto the ramp block. At this time, a tab formed on a front end of the head suspension of the head gimbal assembly is guided along a slope of the ramp block, to move the slider away from the hard disk and prevent the slider from contacting the hard disk during the stoppage of the hard disk.
When the tab is guided along the slope of the ramp block, friction between the tab and the ramp block may grind the ramp block to produce fine matter that may badly affect the hard disk. The hard disk is also vulnerable to unexpected behavior of the slider that may occur during the load/unload movement.
The head gimbal assembly is driven by a voice coil motor (VCM) when achieving the load/unload movement, or when moved from a track to another track on the hard disk, or when following a track on the hard disk. To correctly achieve these tasks, motion characteristics the head gimbal assembly exhibits during a turn thereof in a radial direction of the hard disk must be correctly measured and optimized.
For this, there is a need of an apparatus for easily measuring the motion characteristics of a head gimbal assembly.
Apparatuses for measuring the motion characteristics of a head gimbal assembly frequently employ high-speed cameras or laser Doppler velocimeters to observe the behavior of a slider of the head gimbal assembly during a load/unload motion or a track-to-track movement. This type of apparatus is disclosed in, for example, Japanese Unexamined Patent Application Publications No. H11-96527 and No. 2006-244582. These related arts are limited in the correctness of measured data because they obtain the data by turning a head gimbal assembly in a radial direction of a hard disk.